This invention relates to newly identified polynucleotides, polypeptides encoded by such polynucleotides, and the use of such polynucleotides and polypeptides. The present invention further relates to inhibiting the production and function of the polypeptides of the present invention.
The gastrointestinal tract is the most common site of both newly diagnosed cancers and fatal cancers occurring each year in the USA, figures are somewhat higher for men than for women. The incidence of colon cancer in the USA is increasing, while that of gastric cancer is decreasing, cancer of the small intestine is rare. The incidence of gastrointestinal cancers varies geographically. Gastric cancer is common in Japan and uncommon in the United States, whereas colon cancer is uncommon in Japan and common in the USA. An environmental etiologic factor is strongly suggested by the statistical data showing that people who move to a high-risk area assume the high risk. Some of the suggested etiologic factors for gastric cancer include aflatoxin, a carcinogen formed by aspergillus flavus and present in contaminated food, smoked fish, alcohol, and Vitamin A and magnesium deficiencies. A diet high in fat and low in bulk, and, possibly, degradation products of sterol metabolism may be the etiologic factors for colon cancer. Certain disorders may predispose to cancer, for example, pernicious anemia to gastric cancer, untreated non-tropical sprue and immune defects to lymphoma and carcinoma, and ulcerative and granulomatous colitis, isolated polyps, and inherited familial polyposis to carcinoma of the colon.
The most common tumor of the colon is adenomatous polyp. Primary lymphoma is rare in the colon and most common in the small intestine.
Adenomatous polyps are the most common benign gastrointestinal tumors. They occur throughout the GI tract, most commonly in the colon and stomach, and are found more frequently in males than in females. They may be single, or more commonly, multiple, and sessile or pedunculated. They may be inherited, as in familial polyposis and Gardener's syndrome, which primarily involves the colon. Development of colon cancer is common in familial polyposis. Polyps often cause bleeding, which may occult or gross, but rarely cause pain unless complications ensue. Papillary adenoma, a less common form found only in the colon, may also cause electrolyte loss and mucoid discharge.
A malignant tumor includes a carcinoma of the colon which may be infiltrating or exophytic and occurs most commonly in the rectosigmoid. Because the content of the ascending colon is liquid, a carcinoma in this area usually does not cause obstruction, but the patient tends to present late in the course of the disease with anemia, abdominal pain, or an abdominal mass or a palpable mass.
The prognosis with colonic tumors depends on the degree of bowel wall-invasion and on the presence of regional lymph node involvement and distant metastases. The prognosis with carcinoma of the rectum and descending colon is quite unexpectedly good. Cure rates of 80 to 90% are possible with early resection before nodal invasion develops. For this reason, great care must be taken to exclude this disease when unexplained anemia, occult gastrointestinal bleeding, or change in bowel habits develop in a previously healthy patient. Complete removal of the lesion before it spreads to the lymph nodes provides the best chance of survival for a patient with cancer of the colon. Detection in an asymptomatic patient by occult-bleeding, blood screening results in the highest five year survival.
Clinically suspected malignant lesions can usually be detected radiologically. Polyps less than 1 cm can easily be missed, especially in the upper sigmoid and in the presence of diverticulosis. Clinically suspected and radiologically detected lesions in the esophagus, stomach or colon can be confirmed by fiber optic endoscopy combined with histologic tissue diagnosis made by directed biopsy and brush sitology. Colonoscopy is another method utilized to detect colon diseases. Benign and malignant polyps not visualized by X-ray are often detected on colonoscopy. In addition, patients with one lesion on X-ray often have additional lesions detected on colonoscopy. Sigmoidoscope examination, however, only detects about 50% of colonic tumors.
The above methods of detecting colon cancer have drawbacks, for example, small colonic tumors may be missed by all of the above-described methods, The importance of detecting colon cancer is also extremely important to prevent metastases.